Abstract

We report on a new class of optical antennas that shorten the excited-state lifetime of optical emitters down to 100 fs in a broad spectral range, while maintaining quantum efficiencies as high as 80%. We combine metal nanoparticles with dielectricstructures and exploit concepts from plasmonics and cavity quantum electrodynamics to maximize the local density of states and suppress dissipation losses in the metal. Our findings bring about the prospect of single-photon sources at the μW power level and promise significant impact on other research fields, including photophysics, ultrafast plasmonics, and Raman spectroscopy.